Human papillomavirus (HPV) infection of anogenital tissues has been implicated as a requisite step in the progression to neoplastic transformation. The role of HPV in cervical cancer has been well elucidated;however, most infections with HPV do not lead to cervical pathology. This leads to the hypothesis that co- factor(s) are present that assist in this process. One of these co-factors that have been elucidated is co- infection with the oncogenic virus, Epstein-Barr (EBV) as HIV+ women co-shedding both HPV and EBV have a 2-4 fold increased risk of cervical pathology. HPV has also been implicated in other anogenital cancers especially anal disease. Both HIV+ and HIV-negative women with cervical disease are also at high risk for developing anal dysplasia and anal cancers related to HPV. The infection rates of the anal canal in HIV+ women are actually higher than cervical but the rates of anal cancer are lower. This implies an even stronger role for co-factor(s) in this process. It has been previously reported that EBV can be detected in anal samples. Preliminary data demonstrates similar detection rates (33%) from archived samples from HIV+ individuals. In addition, anal samples are now being collected from the ongoing longitudinal cohorts of HIV+ and HIV-negative women from New Orleans. Thus, it is hypothesized that EBV is shed from the anus and serves as a co- factor for HPV-related anal disease. If EBV has a similar role in the development of anal cancer as it does in cervical cancer than it follows that: (1) EBV and high oncogenic risk HPV will be present in more anal samples at the time of diagnosis of anal dysplasia than in normal anal tissues (epidemiological relationship), (2) EBV and HPV will be detected in anal samples prior to the development of anal lesions (temporal relationship) and (3) EBV and HPV will be located in diseased anal tissues (spatial relationship). The goal of this competitive revision (NOT-OD-09-058: NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications) is to extend the ongoing study into an examination of the role of EBV in HPV-related anal dysplasia and cancer utilizing the existing clinical cohorts. In addition, anal tissue that will be obtained for pathological diagnosis due to an abnormal anal Pap smear will be examined for the location of EBV and HPV in relation to the anal disease as well as differential gene expression. It is felt that this 2 year proposal will quickly establish a role for EBV in anal dysplasia as well as begin to elucidate the mechanism of interaction between these two oncogenic viruses. These data can then be utilize to secure longer term funding to further explore these interactions at both the clinical (prevention of disease) as well as cellular (mechanism of interaction) level. PUBLIC HEALTH RELEVANCE: Human papillomavirus is the cause of most cases of anal cancer;however, most women infected with this virus do not progress to pre-cancer or cancerous lesions implying the need for co-factors in this process. Accumulated evidence points to another cancer-causing virus, Epstein-Barr virus, (EBV), as the potential co- factor, particularly in those women also infected by the HIV virus. The proposed research will further explore the role of EBV in the development HPV-related anal cancer.